Electric guitar amplifiers, their components and modes of operation are well-known in the art. Although the circuitry associated with electric guitar amplifiers have taken literally thousands of variations and have been incorporated into numerous commercial embodiments made by such famous manufactures as Marshall and Fender, the basic design and layout of a standard electric guitar amplifier is well-known and readily-understood by those skilled in the art.
Essentially, and referring to FIG. 1, the standard electric guitar amplifier 10 includes a pre-amplifier or pre-amp 20 and a power amplifier 30. The pre-amp portion 20 is operative to pre-amplify a signal 40 received from the guitar to a level high enough to be consumed by the power amplifier 30. As is well-known to those skilled in the art, one or more successive modifications to the guitar input signal 40′, 40″, 40′″, such as by EQ, pre-amp gain and presence, that sequentially affect the amplified signal that is ultimately fed to the power amplifier are all part of the pre-amp section 20.
The signal 40′″ ultimately received by the power amplifier 30 is that substantially “amplified” with the subsequent output signal being transmitted to the speaker 50. As is well-known, the more driven the power amplifier 30, which occurs as the volume is increased, the more the power amplifier will affect the tone. As a general rule, the louder the volume the more break-up/distortion/wideness of sound will be generated from the electric guitar amplifier. Numerous other factors also affect the tone and sound of the amplifier, too, which are the topics of countless articles and guitar player websites. Most notable is the choice of amplifier components, and in particular the vacuum tubes incorporated in the pre-amp and power amplifier that can dramatically affect the sounds and tones ultimately produced, which are all ultimately a matter of musician preference.
Electric guitar amplifiers are further typically characterized by the circuit configuration utilized at the power amplifier stage, namely, either Class A or Class A/B. Class A, incorporated into certain well-known vintage amplifiers produced by VOX, are characterized by the fact that the circuit design provides for a current that is flowing at all times through the power tubes. As for Class A/B, a negative “bias” of voltage is applied with at least two tubes conducting approximately 180 degrees out of phase relative one another, as provided by splitter 46 as shown in FIG. 1. As a consequence, one vacuum tube will be caused to “shut off” when an audio wave form is below a certain point while the other tube and associated circuit turns on (i.e., before the first one turns off), and thus reproduces the rest of the wave form. As a consequence, the combination of the two vacuum tubes cooperates to produce the full audio wave form. Such Class A/B circuitry is typically associated with amplifiers produced by Marshall and Fender.
A further feature typically employed with electric guitar amplifiers is the integration of a master volume control, shown as 52 in FIG. 1. Such feature, which was first produced by Marshall in 1975, is integrated between the pre-amp output and the power amplifier to thus overdrive the pre-amp signal. In this regard, the master-volume feature can thus impart a controlled amount of the overdriven signal that is fed to the power amplifier, and consequently causes the amplifier to produce overdriven, distorted signals at reasonable volume levels. In this regard, the master volume essentially allows guitar player to explore levels of overdrive using small signals capable of being contrived to overload to a virtually unlimited degree which would otherwise be impossible to do in the power stage where similar levels of overdrive would unquestionably damage the amplified componentry.
Problematic with master volume controls, however, is that such control is designed to only attenuate the signal fed to the power amplifier, and not amplify it. Indeed, the term “master volume” is actually a misnomer insofar as such control feature performs exactly opposite of what it does. As such, by application of the master volume control feature, the attenuation of the musical signal as it is transmitted from the pre-amplifier to the power amplifier can degrade greatly as the master volume control is turned down. Thus, the guitarist can only “take away” from the signal and not otherwise add to the signal, and deprives the player of a tremendous opportunity to modify the gain at a specific tone selection, and much less ultimately amplify such signal at a specific power amp wattage the guitarist may need or want.
As a consequence, conventional master volume controls are thus very limiting in nature, and do not afford any opportunity to yet selectively amplify a signal fed from a pre-amplifier to a power amplifier that has qualities that many a guitarist would desire but for the limitations of the prior art. Unfortunately, the means for providing such functionality has not been available in the art.